This application is based on and claims the benefit of Italian Patent Application No. MI2000A001202 filed on May 31, 2000, which is incorporated by reference herein.
1. Field of the Invention
The present invention pertains to the telecommunication field and in particular concerns the translation of IP (Internet Protocol) addresses used within a private network into different IP addresses which are known within another (public) network by using a leaky-controlled memory.
2. Description of the Prior Art
The growing development of telecommunications, and in particular of Internet, often creates the problems related to the connection of private networks with public networks through apparatus or network elements. Such interconnection apparatus between a first network and another network substantially have the purpose of routing the information (or packets) received from a host computer of the Internet network and deliver them to the private network host computer requesting so. On the contrary, the connection apparatus have to route the packets received from the private network to the public network. The IP (Internet Protocol) address translation from Local Network Addresses into Public Network Addresses and vice versa plays an essential role in this operation which is carried out by the interconnection apparatus.
The Network Address Translation (NAT) is described in broad terms in RFC1631 that describes the relation between NAT and CIDR (Classless Interdomain Routing) as a possible way to alleviate the problem of the IP address running out. Typically, a company with a private network associates the addresses of its private network with one or more IP addresses which are known outside. This also increases safety since each request entering or emerging from the interconnection node must be subjected to a translation process that offers the opportunity to qualify or certify the request or make it coincident with a previous request.
An evolution of the NAT translation function is represented by the NAPT (Network Address and Port Translation) function that assigns to the IP address also an identification of the interface (or port) which the packet is coming from.
The main disadvantage of both NAT and NAPT functions is that they are implemented in software and therefore they are not able to manage such a translation in real time (they do not support the so-called xe2x80x9cwire speedxe2x80x9d). A further disadvantage of such known solutions is that the number of public network IP addresses corresponds to the number of simultaneous accesses to Internet to be provided and therefore the reduction of the public network IP addresses may be not so considerable as instead it would be advisable. Although the situation improves through the NAPT, such a problem still remains.
In view of the known solutions and problems relevant thereto, the main object of the present invention is to develop an hardware architecture able to support the NAPT translation function with higher flexibility than the flexibility provided by the software-implemented NAPT protocol.
These and further objects are achieved by a method and a device having the features set forth in the respective independent claims. The dependent method and device claims set forth additional features. However, all the claims form an integral part of the present description.
The basic idea of the present invention consists in creating an address translation function by suitable transformation of the characteristic parameters of the input packets, subjected to expiration after a pre-established period of time. The packet characteristic parameters include the source IP address, the source TCP port and possibly the physical port ID of the interconnection apparatus. The transformation that is performed on the characteristic parameters can be defined as a hashing operation which will be better explained later on. The present invention is preferably implemented by a proper equipment, hence by hardware.
The invention will certainly result in being clear in view of the following detailed description, given by way of a mere exemplifying and non limiting example, to be read with reference to the attached drawing sheets.